June 22, 2022
Mr. Brian Albanese
Project Manager
DeKalb County School District
Re: Risk Hazard Analysis
Dresden Elementary School -2449 Dresden Drive, Chamblee, Georgia 30341
Matrix Engineering Group Project Number MEG-302765
Mr. Brian:
Matrix Engineering Group, Inc. (Matrix) has completed a site Risk Hazard Assessment (RHA) for the
Dresden Elementary School at 2449 Dresden Drive, Chamblee, Georgia 30341. Matrix followed the
current Georgia Department of Education (GADOE) Facilities Services Unit document titled "Guide
to School Site Selection". The GADOE requires that a hazard assessment be conducted if any of the
hazards outlined within the GADOE document, within the specified radius of the proposed site, are
identified. This report describes the hazards identified within the study area and presents the site risk
hazard analysis to determine the potential impacts on occupants of the proposed school building.
INTRODUCTION
The subject site is located at 2449 Dresden Drive, Chamblee, Georgia 30341. According to the DeKalb
County Tax Assessor’s website and completed questionnaire, the subject site is 9.1 acres in size (Parcel
ID14 1824505033) and is currently owned by DeKalb County School District.
The subject site is bound by Dresden Drive on the north, Dresden Way on the west, Power Line
Easement on the south and commercial properties on the east. The original school building
constructed in 1965, and subsequent classroom additions in 1967 and 1998, are located on the north
portion of the subject site, along with the bus loop providing ingress and egress to for the Dresden
Drive. A gymnasium building constructed in 1998, and play areas along with play structures, are
located on the south portion of the site. Several mobile trailers and a storage building were noted near
the southeast corner of the school building. The school building appeared to be constructed of
structural masonry with slab-on-grade, basements and brick veneer. Covered concrete sidewalks were
noted connecting the school building and the gymnasium building.
4358 Chamblee Tucker Road, Suite 3
Tucker, GA. 30084|t: 770.448.3124|f: 770.448.5324
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
Based on the USGS topographic maps and our site visit, the topography slopes downward from
maximum elevation of around 970 feet Mean Sea Level (MSL) along the east boundary, to building
pad at elevation of around 960 feet MSL, and continue to slope down to 940 feet MSL at northwest
corner and south corner of the site. The elevation change at the site is approximately 30 feet.
PROPERTIES SURROUNDING THE SCHOOL SITE
Surrounding properties consist primarily of residential and commercial use, as tabulated below:
Direction Adjacent Properties Surrounding Properties
North Residential Properties Residential Properties
South Residential Properties Educational Properties
East Residential Properties Residential Properties
West Residential Properties Commercial Properties
Significant landmarks within a mile radius include Interstate I85, DeKalb – Peachtree Airport, Dresden
Park, North Fork Peachtree Creek, Mary Scott Nature Park, and St. Pius X Catholic High School.
HAZARDS IDENTIFICATION AND EVALUATION
A survey of hazards within a 3-mile radius of the subject site was performed in order to identify potential
hazards that may impact the subject site. Sources of information for this work included, but are not
limited to the Environmental Data Resources Inc. (EDR), National Pipeline Mapping System, US
Energy Information Administration (EIA), Federal Emergency Management Agency (FEMA), US
Department of Interior-Fish and Wildlife Service (FWS), Site reconnaissance, and Google Earth.
A site visit was made on June 10, 2022, to identify other hazards in the area (i.e. chemical plants,
railroads, power lines, etc.) and to verify the information obtained from the various agencies. Table 1
below lists the hazards that were identified within the study area and the impact of each hazard on the
subject site. Refer to the body of the report for further discussions regarding the potential impact.
MATRIX ENGINEERING GROUP 2
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
TABLE 1: Survey of Hazards within the Minimum Search Radius (according to Georgia DOE Guidelines)
LOCATED WITHIN MIN. SEARCH RADIUS
CATEGORY
NO YES IMPACT/NOTES
1. Electrical Transmission Lines rated at 115kV or greater
X Yes. Refer to Page 4 for analysis.
within 300 feet of the subject site.
2. Oil or petroleum products transmission lines within 1
X
mile of the subject site
3. Hazardous Chemical Pipelines within 1 mile of the
X
subject site
4. Natural gas transmission and distribution lines larger
than ten inches in diameter with a pressure of 200 psi X
or more within 1 mile of the subject site
5. Fuel facilities – gas stations within ½-mile of the
X Yes. Refer to Page 5 for analysis.
subject site
6. Propane storage facilities within 1 mile of the subject
X
site
7. Railroads within 1 mile of the subject site X
8. Major highways within ½ mile of the subject site X No. Refer to Page 7 for analysis.
9. Airport approaches or departure paths within 3 miles of
X No. Refer to Page 9 for analysis.
the subject site
10. Industrial/Manufacturing Facilities within 1 mile of the
X
subject site
a. Using or storing hazardous substances as defined
X
under Title 40 CFR 262
b. Emitting hazardous air pollutants as defined under
X
the “Clean Air Act”
c. Emitting hazardous air pollutants as defined under
the 1990 “Clean Air Act Amendment” – Risk X
Management Plan Sec. 112(f)
11. Lakes, rivers, dams, reservoirs, or other bodies of water X
12. Potential flooding because the property is located
X
within the 100-year flood plain or dam breach zone
13. Nuclear waste storage facilities within 3 miles of the
X
subject site
MATRIX ENGINEERING GROUP 3
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
LOCATED WITHIN MIN. SEARCH RADIUS
CATEGORY
NO YES IMPACT/NOTES
14. Munitions or explosive storage or manufacturing within
X No. Refer to Page 10 for analysis.
3 miles of the subject site
15. Landfills within ½ mile of the subject site X No. Refer to Page 10 for analysis.
The following paragraphs discuss assessment of the hazards that were identified within the minimum
search radius of the project area, as specified in the Georgia Department of Education guidelines.
ELECTRICAL TRANSMISSION LINES
Electromagnetic Fields (EMF) and its possible human health effects are a concern for many people.
To evaluate the potential risks of EMF, Matrix Engineering Group Inc.'s representatives reviewed
publications by the Department of Engineering and public Policy of Carnegie Mellon University, the
United States Environmental Protection Agency (EPA), the National Research Council, The New
England Journal of Medicine, The American Cancer Society, and the American Medical Association.
Electric and magnetic fields occur around electrical conductors such as power lines, household
wiring, and appliances. Electrical fields result from the strength of the charge, while magnetic fields
result from the motion of the charge. Hence, they are referred to as electromagnetic fields. The
strength of EMF depends on the voltage of the object creating it and the distance away from that
object. Electric fields are generally most intense around high voltage transmission lines.
In 1995, the American Physical Society (APS) spoke out on the question of power-line EMFs and
health effects. The APS policy statement reads, in part: "The scientific literature and the reports of
reviews by other panels show no consistent, significant link between cancer and power line fields.
While it is impossible to prove that no deleterious health effects occur from exposure to any
environmental factor, it is necessary to demonstrate a consistent, significant, and causal relationship
before one can conclude that such effects do occur. From this standpoint, the conjectures relating
cancer to power line fields have not been scientifically substantiated." (See APS Policy Statement
95.2 reaffirmed in 2005.)
The Health Physics Society (HPS), in a published article regarding high-voltage transmission lines,
concluded that “there are no known health risks that have been conclusively demonstrated to be
caused by living near high-voltage power lines. But science is unable to prove a negative, including
MATRIX ENGINEERING GROUP 4
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
whether low-level EMFs are completely risk free. Most scientists believe that exposure to the low-
level EMFs near power lines is safe, but some scientists continue research to look for possible health
risks associated with these fields. If there are any risks such as cancer associated with living near
power lines, then it is clear that those risks are small”.
The Georgia Department of Education Guidelines recommends that high power transmission lines be
at least 300 feet from the portion of the site to be used for facilities or where students gather.
Based on a review of the Department of U.S. Energy maps as well as the aerial maps, a high
voltage transmission power line, which is operated by GA Power, with voltage at 115Kv was
identified along the southern boundary of the school property. Therefore, the Subject Site is within
the impact zone of the high voltage power lines. Refer to Figure 5 in the Appendix for the location
of the high voltage power lines.
FUEL FACILITIES
There are several fuel facilities located within 0.5 miles to the Subject Site along Buford Highway
and Shallowford Road. The closest one is the Shell gas station at 2706 Shallowford Road NE, which
is about 0.19 miles southeast to the subject site and is therefore selected for analysis.
ALOHA model was used to evaluate the hazard of exposure from an accident on the fuel facility. The
analysis assumes that a leak occurs and the content of the tank empties for a period of time. The
model assumes that a vapor cloud forms that originates from the vehicular source or container
towards the site at an assumed wind speed (typically 10 to 30 miles per hour). The model allows
modeling of various chemicals. The chemical properties are assigned by the ALOHA program. The
program models various sources or accident scenarios, such as chemicals leaking from tanks; vertical
for above storage tanks, horizontal for pipelines, or large transport vehicles or train containers.
Accidents, such as leaks from a vertical tank or a horizontal pipeline can be modeled to determine the
impact zone. Hazard conditions include direct source threat zone, overpressure (blast force),
evaporating puddle, flammable area of vapor cloud, leaking from a hole, radiation from pool fire and
fire ball. The program calculates distances of the Toxic Threat Zone, Flammable Threat Zone,
Thermal Radiation Threat Zone from pool fire, Threat Zone from a fireball and Threat at a point for a
specific designated downwind distance including outdoor and indoor concentrations of the modeled
MATRIX ENGINEERING GROUP 5
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
chemical. The model displays a test summary that includes the assumed parameters and displays the
model results. When applicable, the results are displayed on graphs showing the potential Threat
Levels based on established Guideline of Exposure Limits, such as Acute Exposure Guidelines limits
(AEGL-1, AEGL-2 and AEGL-3) with concentrations based on the type of gas modeled.
Additionally, blast force from vapor cloud explosion (overpressure) is estimated at a point and
evaluated based a 60-second blast force. The model also provides the outdoor and indoor
concentration of the specific chemical modeled.
Benzene was selected for ALOHA modeling.
The model results were compared to the following criteria as appropriate:
Threat Modeled: Toxic Area of Vapor Cloud: AEGL-1 (52 ppm), AEGL-2 (800 ppm), and
AEGL-3 (4000 ppm)
Threat Modeled: Flammable Area of Vapor Cloud: = 60% LEL (Flame Pockets= 6600 ppm)
and 10% LEL (1100 ppm)
Threat Modeled: Overpressure (blast force) from vapor cloud explosion, ignited by spark or
flame
o Destruction of buildings at a blast force of 8.0 psi
o Serious injury likely at a blast force of 3.5 psi
o Shatters glass at a blast force of 1.0 psi
Threat Modeled: Thermal radiation from pool fire
o Potentially lethal within 60 sec at 10.0 kW/(sq m)
o Second degree burns within 60 sec at 5.0 kW/(sq m)
o Pain within 60 sec at 2.0 kW/(sq m)
Outdoor and Indoor Concentration: AEGL-1 for Benzene at 52 ppm.
The ALOHA test results are provided in the Appendix of this report. Based on the test results, the
following is our findings:
The Toxic Threat Zone distance for tank model were 654 yards, 76 yards, and 39 yards for
AEGL-1 (52 ppm), AEGL-2 (400 ppm), and AEGL-3 (4000 ppm), respectively. The subject
site is located in the Toxic Threat Zone.
MATRIX ENGINEERING GROUP 6
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
The Overpressure (blast force) from vapor cloud explosion was not exceeded and will not
impact the subject site.
The Flammable Area of Vapor Cloud of 60% LEL (Flame Pockets= 6600 ppm) and 10%
LEL (1100 ppm) are 39 yards and 88 yards respectively. The subject site is not located in the
Flammable Area.
The Thermal Radiation Levels from a pool fire were 46 yards, 60 yards, and 85 yards for the
10.0 kW/sq.m, 5.0 kW/sq.m, and 2.0 kW/sq.m, respectively. The subject site is not within
the impact distance.
Maximum Outdoor Concentrations were 84.1 ppm and Indoor Concentrations were at 38.2 ppm for
toxic vapor cloud resulted from the accident on Shell gas station. The Maximum Outdoor
Concentration is above levels for AEGL-1 for Benzene at 52 ppm. Refer to the recommendations
section for general recommendations to mitigate outdoor/indoor potential presence of hazards in the
atmosphere.
Based on our site reconnaissance, the location of the petroleum facility, and ALOHA model, the
subject site is located within the impact zone of a major accident on Shell gas station. Refer to the
Hazard Risk Assessment Findings, Recommendations and Site Suitability Statement section on
page 11 of this report for recommended mitigation measures.
MAJOR ROADWAYS
Buford Highway is located approximately 0.25 mile northwest of the subject site; and Interstate I-85
is located approximately 0.29 mile southeast of the subject site. Tankers carrying gasoline products
are likely to use the roadways to transport to nearby gas stations. Buford Highway is selected for
modeling.
The ALOHA model was used to evaluate the hazard of exposure from an accident on Buford
Highway. Since ALOHA does not model liquids, the analysis assumes that a leak occurs and the
contents of the tank empties for a period of time. The model assumes that a vapor cloud forms that
originates from the vehicular source or container towards the site at an assumed wind speed (typically
10 to 30 miles per hour). The model allows modeling of various chemicals. The chemical properties
are assigned by the ALOHA program. The program models various sources or accident scenarios,
such as chemicals leaking from tanks; vertical for above storage tanks, horizontal for pipelines, or
MATRIX ENGINEERING GROUP 7
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
large transport vehicles or train containers. Accidents, such as leaks from a vertical tank or a
horizontal pipeline can be modeled to determine the impact zone. Hazard conditions includes direct
source threat zone, overpressure (blast force), evaporating puddle, flammable area of vapor cloud,
leaking from a hole, radiation from pool fire and fire ball. The program calculates distances of the
Toxic Threat Zone, Flammable Threat Zone, Thermal Radiation Threat Zone from pool fire, Threat
Zone from a fireball and Threat at a point for a specific designated downwind distance including
outdoor and indoor concentrations of the modeled chemical. The model displays a test summary that
includes the assumed parameters and displays the model results. When applicable, the results are
displayed on graphs showing the potential Threat Levels based on established Guideline of Exposure
Limits, such as Acute Exposure Guidelines limits (AEGL-1, AEGL-2 and AEGL-3) with
concentrations based on the type of gas modeled. Additionally, blast force from vapor cloud
explosion (overpressure) is estimated at a point and evaluated based a 60-second blast force. The
model also provides the outdoor and indoor concentration of the specific chemical molded.
Benzene was selected for ALOHA modeling.
The model results were compared to the following criteria as appropriate:
Threat Modeled: Toxic Area of Vapor Cloud: AEGL-1 (52 ppm), AEGL-2 (800 ppm), and
AEGL-3 (4000 ppm)
Threat Modeled: Flammable Area of Vapor Cloud: = 60% LEL (Flame Pockets= 6600 ppm)
and 10% LEL (1100 ppm)
Threat Modeled: Overpressure (blast force) from vapor cloud explosion, ignited by spark or
flame
o Destruction of buildings at a blast force of 8.0 psi
o Serious injury likely at a blast force of 3.5 psi
o Shatters glass at a blast force of 1.0 psi
Threat Modeled: Thermal radiation from pool fire
o Potentially lethal within 60 sec at 10.0 kW/(sq m)
o Second degree burns within 60 sec at 5.0 kW/(sq m)
o Pain within 60 sec at 2.0 kW/(sq m)
Outdoor and Indoor Concentration: AEGL-1 for Benzene at 52 ppm.
The ALOHA test results are provided in the Appendix of this report. Based on the test results, the
following is our findings:
MATRIX ENGINEERING GROUP 8
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
The Toxic Threat Zone distance for tank model were 423 yards, 50 yards, and 25 yards for
AEGL-1 (52 ppm), AEGL-2 (400 ppm), and AEGL-3 (4000 ppm), respectively. The subject
site is not located in the Toxic Threat Zone.
The Overpressure (blast force) from vapor cloud explosion was not exceeded and will not
impact the subject site.
The Flammable Area of Vapor Cloud of 60% LEL (Flame Pockets= 6600 ppm) and 10%
LEL (1100 ppm) are 25 yards and 57 yards respectively. The subject site is not located in the
Flammable Area.
The Thermal Radiation Levels from a pool fire were 46 yards, 60 yards, and 85 yards for the
10.0 kW/sq.m, 5.0 kW/sq.m, and 2.0 kW/sq.m, respectively. The subject site is not within
the impact distance.
Maximum Outdoor Concentrations were 13.6 ppm and Indoor Concentrations were at 5.02 ppm for
toxic vapor cloud resulted from the accident on Buford Highway. The Maximum Outdoor and Indoor
Concentrations are below levels for AEGL-1 for Benzene at 52 ppm. Refer to the recommendations
section for general recommendations to mitigate outdoor/indoor potential presence of hazards in the
atmosphere.
Based on our site reconnaissance, the location of the petroleum facility, and ALOHA model, the
subject site is not located within the impact zone of a major accident on Buford Highway. Refer to the
Hazard Risk Assessment Findings, Recommendations and Site Suitability Statement section on
page 11 of this report for recommended mitigation measures.
AIRPORT
The nearest airport is DeKalb Peachtree Airport located at 2000 Airport Road, Atlanta, Georgia
30041. The southeast border of the Airport is located approximately 0.42 miles from the subject site.
The DeKalb Peachtree Airport has two runways. Runway 34/16 is aligned in a Northwest to
Southeast direction; and Runway 21/3 is aligned in a Northeast to Southwest direction. The runways
are served by parallel taxiways to connect to the airport hangers and facilities.
MATRIX ENGINEERING GROUP 9
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
Google maps were used to estimate the distances as well as the projection of the 3-mile airplanes path
for approach and take-off. The DOE Guidelines states that the school site should not be in line with
an airport runway within a 3-mile distance. Based on Google Maps measurements, the site is not
directly in line with the runway. The site is located at an offset of approximately 0.3 miles north of
the projected runway 34/16 alignment.
MUNITIONS OR EXPLOSIVE STORAGE
According to EDR Radius Report, several Formerly Used Defense Sites (FUDS) properties and
Unexploded Ordnance (UXO) sites were located within 3 miles of the subject site, including the
HILLTOP TRANSMITTAL SITE, NAS ATLANTA, I04GA097500 - MMRP/CWM, and CP
GORDON in Chamblee, Georgia. Based on EDR records, these facilities were mainly used for
training purposes and were closed in the 1940s and 1950s.
For the NAS ATLANTA site: The U.S. acquired approximately 408.71 acres for this site, which was
later purchased by Dekalb County to build an airport. Between 1940 and 1953, the U.S. acquired land
for use as a Naval Reserve aviation base, including DeKalb County Airport. The site was a complete
pilot training base, including housing and support facilities. It was declared excess in 1958. In
February 1960, a quitclaim deed conveyed the land and improvements to DeKalb County. The site is
currently being used by the county as a general aviation facility known as DeKalb-Peachtree Airport.
This property is known or suspected to contain military munitions and explosives of concern (e.g.,
unexploded ordnance) and therefore may present an explosive hazard.
Due to limited available information, it was assumed that the storage or manufacturing of explosives
occurs at the west and north side of the airport, where most buildings are located. Based on USGS
Maps, the buildings are at an approximate elevation of 940 to 1010 feet MSL, which is approximately
30 to 70 feet higher than that of the subject site. The area between the building and subject site is
mostly developed with residential and commercial properties, and there is no direct line of sight.
Therefore, it is our opinion that the impact of an explosion at the DeKalb-Peachtree Airport is
unlikely to impact the subject site.
LANDFILL
According to EDR Radius Report, there was a Historical Landfill along Buford Highway that was
about 0.386 miles north to northwest of the subject site. Based on EDR records, the landfill was a
MATRIX ENGINEERING GROUP 10
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
public Unlined Sanitary Landfill that was now closed. The elevation of the Historical Landfill was
approximately 951 feet MSL, which was on the close to the majority area of the subject site. A
tributary of the North Fork Peachtree Creek was in between the Historical Landfill and the subject
site. Based on the distance, topography, and hydrology features, the Historical Landfill is unlikely to
impact the subject site.
RESPONDERS
One of the first responders will be the DeKalb County Fire Station 15, which is located approximately
1.15 miles northwest of the subject site at 2017 Flight Way Drive, Atlanta, GA 30341. Based on the
location of the Fire Station, response to any major accident would be within a few minutes. Three
additional fire stations are strategically located around the site, namely, DeKalb County Fire Station
19 located at 3253 Mercer University Drive, Atlanta, GA 30341 approximately 2.1 miles east of the
subject site; DeKalb County Fire Station 2 located at 1316 Dresden Drive, Atlanta, GA 30341,
approximately 2.53 miles west of the subject site; and DeKalb County Fire Station 8 located at 2711
Clairmont Road, Atlanta, GA 30329 approximately 2.56 miles southwest of the subject site.
Per previous discussions with the Fire Department, response to a subject site would be approximately
5 minutes. Assistance by the neighboring fire stations will be available on an as needed basis and
their response time is approximately 6 to 10 minutes for the project site. These Fire Stations
are equipped with Engine 15, 2, 8, and 19, Crash 15, Battalion 1 and HAZMAT 19. If an accident
occurs at the site or in the vicinity of the site, then the first responder would consist of DeKalb
County Fire Station 15, 19, 2 and 8. If additional help is needed, it would be provided by the
neighboring localities.
Based on the locations of the fire station with respect to the subject site, it is our opinion that adequate
facilities should be available in the event of a major accident.
HAZARD RISK ASSESSMENT CONCLUSION AND RECOMMENDATIONS
The potential hazards that were identified within the minimum GADOE evaluation radius from the
site included high voltage power transmission line, fuel facilities, major roadways, airports, munitions
or explosive storage, and landfill. The foremost concern associated with the majority of theses
hazards would be by accidental causes on the fuel facilities and major roadways. The probability of
such accidents occurring is highly dependent upon several factors, including weather conditions and
MATRIX ENGINEERING GROUP 11
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
the human element and is therefore difficult, if not impossible, to predict. For this reason, we have not
attempted to evaluate probabilities but have focused instead on the facts and availability of potential
responders in most cases.
CONCLUSIONS
1. Based on our site reconnaissance, the southern area of the subject site is located within the
impact zone of a high voltage electrical transmission line. The GA DOE requires that the
proposed development should be located greater than 300 feet from the transmission lines and
be fenced off to limit access to students.
2. Based on our site reconnaissance, the location of the fuel facility, and the ALOHA model, the
subject site is located within the impact zone of a major accident on the fuel facility.
3. Based on our site reconnaissance, the location of the major roadway, and the ALOHA model,
the subject site is not located within the impact zone of a major accident along Buford
Highway.
4. Based on our site reconnaissance, the location, the distance and the alignment of the airport
runway, subject site is not located within the impact zone of accidents along the airport
runway.
5. Based on our site reconnaissance, the location, the distance, subject site is not located within
the impact zone of accidents from the munitions and explosive storage facilities.
6. Based on our site reconnaissance, the location, the distance and topography and hydrology
features, subject site is not located within the impact zone of the Historical Landfill.
RECOMMENDATIONS
Based on the information gathered in this study and our analysis, the site appears to be inside the zone
of direct impact of a major accident on the high voltage power transmission line and fuel facilities.
Based on the DOE guidelines, we recommend the school board incorporate the following measures
into the planning and design of the school building:
1. The proposed development on the south area of the site should meet the minimum
requirements of 300 feet away from the high voltage transmission power lines. Access to
students should be limited with a fence.
2. Prepare an emergency preparedness plan to address the potential hazards referenced in
this report.
MATRIX ENGINEERING GROUP 12
Tucker, Georgia
Site Risk Hazard Assessment June 22, 2022
Dresden Elementary School MEG Project No. 302765
3. Prepare an evacuation plan consistent with the type of hazard identified to provide for
efficient and timely evacuation of the buildings in case of an emergency.
4. Install fencing at the perimeter of the school building and facilities to restrict students
from leaving and to limit access to school site.
5. Design of air handling and ventilation systems should incorporate engineering controls to
prevent intrusion of hazardous airborne contaminant (i.e. shut-off system, detection
devices, and control air circulation and purging of contaminant from the building
envelope).
Based on the Hazard Risk Analysis and our Evaluation for the Dresden Elementary School, it is
our opinion that the subject site is suitable for the proposed development provided that the
mitigation measures recommended in this report are incorporated into the design and
operation of the school facility.
Matrix Engineering Group, Inc. appreciates the opportunity of working with you on this project and
look forward to our continued association. If you have any questions concerning this report, please
contact us.
Yours truly,
MATRIX ENGINEERING GROUP, INC.
Qinghe Lou, PE Sam Alyateem, PE
Project Engineer Principal
M:\1.0 MATRIX PROJECTS FOLDER\Dresden Elementary School (DeKalb Co. Schools)\1.0 ENVIRONMENTAL - MEG 302765\RHA\report\Dresden ES Risk Hazard Analysis Report.doc
MATRIX ENGINEERING GROUP 13
Tucker, Georgia
APPENDIX
SITE LOCATION MAP
3-MILE RADIUS HAZARDS MAP
NATIONAL FLOOD HAZARD MAP
NATIONAL WETLANDS INVENTORY MAP
ALOHA MODELING
TITLE
SITE LOCATION
PROJECT
DRESDEN ELEMENTARY SCHOOL
Rail Roads PROJECT NUMBER
Subject Site MEG302765
CLIENT
DEKALB COUNTY SCHOOL DISTRICT
Subject Site
SCALE
NTS
115Kv Transmission REVIEWED
Lines
SAM ALYATEEM, PE
DATE
Major Roadway - Stone 6/16/2022
Mountain Hwy (Hwy 78) FIGURE
1
LEGEND
TITLE
HAZARDS IDENTIFIED WITHIN 3-MILE
RADIUS
PROJECT
DRESDEN ELEMENTARY SCHOOL
PROJECT NUMBER
MEG302765
CLIENT
DEKALB COUNTY SCHOOL DISTRICT
SCALE
NTS
REVIEWED
SAM ALYATEEM, PE
DATE
6/16/2022
FIGURE
2
LEGEND
Landfill
Powerline
Major Roadways
Airport Runways
Munitions or Explosive Storage
Fuel Facility
TITLE
FLOOD MAP
PROJECT
DRESDEN ELEMENTARY SCHOOL
Rail Roads PROJECT NUMBER
AGL Gas Pipeline Subject Site MEG302765
CLIENT
DEKALB COUNTY SCHOOL DISTRICT
Subject Site
SCALE
NTS
115Kv Transmission REVIEWED
Lines
SAM ALYATEEM, PE
DATE
Major Roadway - Stone 6/16/2022
Mountain Hwy (Hwy 78) FIGURE
3
LEGEND
TITLE
WETLANDS MAP
PROJECT
DRESDEN ELEMENTARY SCHOOL
Subject Site
Rail Roads PROJECT NUMBER
AGL Gas Pipeline Subject Site SUBJECT SITE MEG302765
CLIENT
DEKALB COUNTY SCHOOL DISTRICT
Subject Site
SCALE
NTS
115Kv Transmission REVIEWED
Lines
SAM ALYATEEM, PE
DATE
Major Roadway - Stone 6/16/2022
Mountain Hwy (Hwy 78) FIGURE
4
LEGEND
TITLE
POWERLINE MAP
PROJECT
DRESDEN ELEMENTARY SCHOOL
Subject Site
Rail Roads PROJECT NUMBER
AGL Gas Pipeline Subject Site Subject Site SUBJECT SITE MEG302765
CLIENT
DEKALB COUNTY SCHOOL DISTRICT
Subject Site
SCALE
NTS
115Kv Transmission REVIEWED
Lines
SAM ALYATEEM, PE
DATE
Major Roadway - Stone 6/21/2022
Mountain Hwy (Hwy 78) FIGURE
5
LEGEND
Fuel Facility
Toxic Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1041 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from SE at 3 meters
THREAT ZONE:
Model Run: Gaussian
Red : 39 yards --- (4000 ppm = AEGL-3 [60 min])
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Orange: 76 yards --- (800 ppm = AEGL-2 [60 min])
Note: Threat zone was not drawn because dispersion predictions are
unreliable for lengths less than the maximum diameter of the puddle.
Maximum diameter of the puddle: 78 yards
Yellow: 654 yards --- (52 ppm = AEGL-1 [60 min])
yards
300
100
wind
0
100
300
200 0 200 400 600 800
yards
greater than 4000 ppm (AEGL-3 [60 min]) (not drawn)
greater than 800 ppm (AEGL-2 [60 min]) (not drawn)
greater than 52 ppm (AEGL-1 [60 min])
wind direction confidence lines
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1041 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from SE at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 16 feet Tank Length: 16 feet
Tank Volume: 24,065 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 87.5 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 8.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: ALOHA limited the duration to 1 hour
Max Average Sustained Release Rate: 1,520 pounds/min
(averaged over a minute or more)
Total Amount Released: 70,143 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 78 yards.
THREAT ZONE:
Model Run: Gaussian
Red : 39 yards --- (4000 ppm = AEGL-3 [60 min])
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Orange: 76 yards --- (800 ppm = AEGL-2 [60 min])
Note: Threat zone was not drawn because dispersion predictions are
unreliable for lengths less than the maximum diameter of the puddle.
Maximum diameter of the puddle: 78 yards
Yellow: 654 yards --- (52 ppm = AEGL-1 [60 min])
Concentration at Point ALOHA® 5.4.7
Time: June 10, 2022 1309 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
THREAT AT POINT:
Model Run: Gaussian
Concentration Estimates at the point:
West: 580 feet North: 1200 feet
Max Concentration:
Outdoor: 84.1 ppm
Indoor: 38.2 ppm
ppm
100
80
60
AEGL-1 (60 min)
40
20
0
0 10 30 20 40 50 60
minutes
Outdoor Concentration
Indoor Concentration
At Point: West: 580 feet North: 1200 feet
Source Strength (Evaporation Rate) ALOHA® 5.4.7
Time: June 10, 2022 1309 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 16 feet Tank Length: 16 feet
Tank Volume: 24,065 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 87.5 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 8.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: ALOHA limited the duration to 1 hour
Max Average Sustained Release Rate: 1,540 pounds/min
(averaged over a minute or more)
Total Amount Released: 71,333 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 78 yards.
pounds/minute
2,000
1,500
1,000
500
0
0 10 20 30 40 50 60
minutes
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1309 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from SSE at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 16 feet Tank Length: 16 feet
Tank Volume: 24,065 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 87.5 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 8.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: ALOHA limited the duration to 1 hour
Max Average Sustained Release Rate: 1,540 pounds/min
(averaged over a minute or more)
Total Amount Released: 71,333 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 78 yards.
THREAT AT POINT:
Concentration Estimates at the point:
West: 580 feet North: 1200 feet
Max Concentration:
Outdoor: 84.1 ppm
Indoor: 38.2 ppm
Overpressure (Blast Force) Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1309 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from SSE at 3 meters
THREAT ZONE:
Threat Modeled: Overpressure (blast force) from vapor cloud explosion
Type of Ignition: ignited by spark or flame
Level of Congestion: uncongested
Model Run: Gaussian
No explosion: no part of the cloud is above the LEL at any time
Threat Modeled: Overpressure (blast force) from vapor cloud
Type of Ignition: ignited by spark or flame
Level of Congestion: uncongested
Model Run: Gaussian
No explosion: no part of the cloud is above the LEL at any t
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1309 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from SSE at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 16 feet Tank Length: 16 feet
Tank Volume: 24,065 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 87.5 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 8.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: ALOHA limited the duration to 1 hour
Max Average Sustained Release Rate: 1,540 pounds/min
(averaged over a minute or more)
Total Amount Released: 71,333 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 78 yards.
THREAT ZONE:
Threat Modeled: Overpressure (blast force) from vapor cloud explosion
Type of Ignition: ignited by spark or flame
Level of Congestion: uncongested
Model Run: Gaussian
No explosion: no part of the cloud is above the LEL at any time
Flammable Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1309 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from SSE at 3 meters
THREAT ZONE:
Threat Modeled: Flammable Area of Vapor Cloud
Model Run: Gaussian
Red : 39 yards --- (7200 ppm = 60% LEL = Flame Pockets)
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Yellow: 88 yards --- (1200 ppm = 10% LEL)
yards
75
25
wind
0
25
75
50 0 50 100 150
yards
greater than 7200 ppm (60% LEL = Flame Pockets) (not dra
greater than 1200 ppm (10% LEL)
wind direction confidence lines
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1309 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from SSE at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 16 feet Tank Length: 16 feet
Tank Volume: 24,065 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 87.5 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 8.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: ALOHA limited the duration to 1 hour
Max Average Sustained Release Rate: 1,540 pounds/min
(averaged over a minute or more)
Total Amount Released: 71,333 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 78 yards.
THREAT ZONE:
Threat Modeled: Flammable Area of Vapor Cloud
Model Run: Gaussian
Red : 39 yards --- (7200 ppm = 60% LEL = Flame Pockets)
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Yellow: 88 yards --- (1200 ppm = 10% LEL)
THREAT AT POINT:
Concentration Estimates at the point:
West: 580 feet North: 1200 feet
Max Concentration:
Outdoor: 84.1 ppm
Indoor: 38.2 ppm
Thermal Radiation Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1309 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from SSE at 3 meters
THREAT ZONE:
Threat Modeled: Thermal radiation from pool fire
Red : 46 yards --- (10.0 kW/(sq m) = potentially lethal within 60 sec)
Orange: 60 yards --- (5.0 kW/(sq m) = 2nd degree burns within 60 sec)
Yellow: 85 yards --- (2.0 kW/(sq m) = pain within 60 sec)
yards
100
50
wind
0
50
100
100 50 0 50 100 150
yards
greater than 10.0 kW/(sq m) (potentially lethal within
greater than 5.0 kW/(sq m) (2nd degree burns within 60
greater than 2.0 kW/(sq m) (pain within 60 sec)
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1309 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from SSE at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical is burning as it escapes from tank
Tank Diameter: 16 feet Tank Length: 16 feet
Tank Volume: 24,065 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 87.5 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 8.00 feet from tank bottom
Max Puddle Diameter: Unknown
Max Flame Length: 26 yards Burn Duration: 50 minutes
Max Burn Rate: 1,960 pounds/min
Total Amount Burned: 87,493 pounds
Note: The chemical escaped as a liquid and formed a burning puddle.
The puddle spread to a diameter of 16.5 yards.
THREAT ZONE:
Threat Modeled: Thermal radiation from pool fire
Red : 46 yards --- (10.0 kW/(sq m) = potentially lethal within 60 sec)
Orange: 60 yards --- (5.0 kW/(sq m) = 2nd degree burns within 60 sec)
Yellow: 85 yards --- (2.0 kW/(sq m) = pain within 60 sec)
Major Highway
Toxic Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1309 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from SSE at 3 meters
THREAT ZONE:
Model Run: Gaussian
Red : 25 yards --- (4000 ppm = AEGL-3 [60 min])
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Orange: 50 yards --- (800 ppm = AEGL-2 [60 min])
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Yellow: 423 yards --- (52 ppm = AEGL-1 [60 min])
yards
200
100
wind
0
100
200
100 0 100 200 300 400 500
yards
greater than 4000 ppm (AEGL-3 [60 min]) (not drawn)
greater than 800 ppm (AEGL-2 [60 min]) (not drawn)
greater than 52 ppm (AEGL-1 [60 min])
wind direction confidence lines
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1309 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from SSE at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 8 feet Tank Length: 16.0 feet
Tank Volume: 6000 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 21.8 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 4.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: 36 minutes
Max Average Sustained Release Rate: 652 pounds/min
(averaged over a minute or more)
Total Amount Released: 21,800 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 50 yards.
THREAT ZONE:
Model Run: Gaussian
Red : 25 yards --- (4000 ppm = AEGL-3 [60 min])
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Orange: 50 yards --- (800 ppm = AEGL-2 [60 min])
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Yellow: 423 yards --- (52 ppm = AEGL-1 [60 min])
Concentration at Point ALOHA® 5.4.7
Time: June 10, 2022 1318 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
THREAT AT POINT:
Model Run: Gaussian
Concentration Estimates at the point:
East: 1900 feet South: 600 feet
Max Concentration:
Outdoor: 13.6 ppm
Indoor: 5.02 ppm
ppm
20
15
10
5
0
0 10 20 30 40 50 60
minutes
Outdoor Concentration
Indoor Concentration
At Point: East: 1900 feet South: 600 feet
Source Strength (Evaporation Rate) ALOHA® 5.4.7
Time: June 10, 2022 1318 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 8 feet Tank Length: 16.0 feet
Tank Volume: 6000 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 21.8 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 4.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: 36 minutes
Max Average Sustained Release Rate: 652 pounds/min
(averaged over a minute or more)
Total Amount Released: 21,800 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 50 yards.
pounds/minute
800
600
400
200
0
0 10 20 30 40
minutes
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1318 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from WNW at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 8 feet Tank Length: 16.0 feet
Tank Volume: 6000 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 21.8 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 4.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: 36 minutes
Max Average Sustained Release Rate: 652 pounds/min
(averaged over a minute or more)
Total Amount Released: 21,800 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 50 yards.
THREAT AT POINT:
Concentration Estimates at the point:
East: 1900 feet South: 600 feet
Max Concentration:
Outdoor: 13.6 ppm
Indoor: 5.02 ppm
Overpressure (Blast Force) Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1318 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from WNW at 3 meters
THREAT ZONE:
Threat Modeled: Overpressure (blast force) from vapor cloud explosion
Type of Ignition: ignited by spark or flame
Level of Congestion: uncongested
Model Run: Gaussian
No explosion: no part of the cloud is above the LEL at any time
Threat Modeled: Overpressure (blast force) from vapor cloud
Type of Ignition: ignited by spark or flame
Level of Congestion: uncongested
Model Run: Gaussian
No explosion: no part of the cloud is above the LEL at any t
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1318 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from WNW at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 8 feet Tank Length: 16.0 feet
Tank Volume: 6000 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 21.8 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 4.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: 36 minutes
Max Average Sustained Release Rate: 652 pounds/min
(averaged over a minute or more)
Total Amount Released: 21,800 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 50 yards.
THREAT ZONE:
Threat Modeled: Overpressure (blast force) from vapor cloud explosion
Type of Ignition: ignited by spark or flame
Level of Congestion: uncongested
Model Run: Gaussian
No explosion: no part of the cloud is above the LEL at any time
Flammable Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1318 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from WNW at 3 meters
THREAT ZONE:
Threat Modeled: Flammable Area of Vapor Cloud
Model Run: Gaussian
Red : 25 yards --- (7200 ppm = 60% LEL = Flame Pockets)
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Yellow: 57 yards --- (1200 ppm = 10% LEL)
yards
50
30
10
wind
0
10
30
50
40 20 0 20 40 60 80
yards
greater than 7200 ppm (60% LEL = Flame Pockets) (not d
greater than 1200 ppm (10% LEL)
wind direction confidence lines
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1318 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from WNW at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical escaping from tank (not burning)
Tank Diameter: 8 feet Tank Length: 16.0 feet
Tank Volume: 6000 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 21.8 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 4.00 feet from tank bottom
Ground Type: Default soil
Ground Temperature: equal to ambient
Max Puddle Diameter: Unknown
Release Duration: 36 minutes
Max Average Sustained Release Rate: 652 pounds/min
(averaged over a minute or more)
Total Amount Released: 21,800 pounds
Note: The chemical escaped as a liquid and formed an evaporating puddle.
The puddle spread to a diameter of 50 yards.
THREAT ZONE:
Threat Modeled: Flammable Area of Vapor Cloud
Model Run: Gaussian
Red : 25 yards --- (7200 ppm = 60% LEL = Flame Pockets)
Note: Threat zone was not drawn because effects of near-field patchiness
make dispersion predictions less reliable for short distances.
Yellow: 57 yards --- (1200 ppm = 10% LEL)
THREAT AT POINT:
Concentration Estimates at the point:
East: 1900 feet South: 600 feet
Max Concentration:
Outdoor: 13.6 ppm
Indoor: 5.02 ppm
Thermal Radiation Threat Zone ALOHA® 5.4.7
Time: June 10, 2022 1318 hours EDT (using computer's clock)
Chemical Name: BENZENE
Carcinogenic risk - see CAMEO Chemicals
Wind: 12 miles/hour from WNW at 3 meters
THREAT ZONE:
Threat Modeled: Thermal radiation from pool fire
Red : 46 yards --- (10.0 kW/(sq m) = potentially lethal within 60 sec)
Orange: 60 yards --- (5.0 kW/(sq m) = 2nd degree burns within 60 sec)
Yellow: 85 yards --- (2.0 kW/(sq m) = pain within 60 sec)
yards
100
50
wind
0
50
100
100 50 0 50 100 150
yards
greater than 10.0 kW/(sq m) (potentially lethal within
greater than 5.0 kW/(sq m) (2nd degree burns within 60
greater than 2.0 kW/(sq m) (pain within 60 sec)
Text Summary ALOHA® 5.4.7
SITE DATA:
Location: CHAMBLEE, GEORGIA
Building Air Exchanges Per Hour: 0.83 (sheltered single storied)
Time: June 10, 2022 1318 hours EDT (using computer's clock)
CHEMICAL DATA:
Chemical Name: BENZENE
CAS Number: 71-43-2 Molecular Weight: 78.11 g/mol
AEGL-1 (60 min): 52 ppm AEGL-2 (60 min): 800 ppm AEGL-3 (60 min): 4000 ppm
IDLH: 500 ppm LEL: 12000 ppm UEL: 80000 ppm
Carcinogenic risk - see CAMEO Chemicals
Ambient Boiling Point: 174.2° F
Vapor Pressure at Ambient Temperature: 0.13 atm
Ambient Saturation Concentration: 139,450 ppm or 13.9%
ATMOSPHERIC DATA: (MANUAL INPUT OF DATA)
Wind: 12 miles/hour from WNW at 3 meters
Ground Roughness: urban or forest Cloud Cover: 5 tenths
Air Temperature: 80° F Stability Class: D
No Inversion Height Relative Humidity: 50%
SOURCE STRENGTH:
Leak from hole in horizontal cylindrical tank
Flammable chemical is burning as it escapes from tank
Tank Diameter: 8 feet Tank Length: 16.0 feet
Tank Volume: 6000 gallons
Tank contains liquid Internal Temperature: 80° F
Chemical Mass in Tank: 21.8 tons Tank is 100% full
Circular Opening Diameter: 0.5 feet
Opening is 4.00 feet from tank bottom
Max Puddle Diameter: Unknown
Max Flame Length: 26 yards Burn Duration: 15 minutes
Max Burn Rate: 1,960 pounds/min
Total Amount Burned: 21,800 pounds
Note: The chemical escaped as a liquid and formed a burning puddle.
The puddle spread to a diameter of 16.5 yards.
THREAT ZONE:
Threat Modeled: Thermal radiation from pool fire
Red : 46 yards --- (10.0 kW/(sq m) = potentially lethal within 60 sec)
Orange: 60 yards --- (5.0 kW/(sq m) = 2nd degree burns within 60 sec)
Yellow: 85 yards --- (2.0 kW/(sq m) = pain within 60 sec)